|Publication number||US7350734 B2|
|Application number||US 11/251,168|
|Publication date||Apr 1, 2008|
|Filing date||Oct 13, 2005|
|Priority date||Oct 13, 2005|
|Also published as||US20070085318|
|Publication number||11251168, 251168, US 7350734 B2, US 7350734B2, US-B2-7350734, US7350734 B2, US7350734B2|
|Inventors||Bruce A. Stevens|
|Original Assignee||Automotive Systems Laboratory, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (63), Referenced by (21), Classifications (7), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Safety belt pretensioners remove slack from a safety belt in the event of a collision in order to minimize forward movement of the passenger. It is known to use pyrotechnic gas generators to operate pretensioner mechanisms that wind up or otherwise pull in slack in the safety belt during a collision. Such pyrotechnic gas generators are often disposed internally of a safety belt retractor. High-temperature gases tend to abrade interior metal surfaces and produce ash and clinkers that bind up the retraction mechanism. Thus, the vehicle owner is faced with a significant cost penalty in that the entire pretensioner and retractor assembly must be replaced after activation because of the inability to prevent degradation of the retractor.
Further, where pyrotechnic gas generators are used to supply the rapidly increasing gas pressure for the pretensioner, the gas pressurization rate and the resultant initial driving force or acceleration of the piston can exceed the structural capability of the driven components. As a result, the entire pretensioner assembly can malfunction due to fracturing of a given part. If damaged due to application of excessive forces, the retractor will not retract and function as a load limiter during a second impact. Thus, the retractor must be replaced.
In addition, many existing retractor designs incorporate the pretensioner into the retractor assembly. In these designs, the retractor tends to occupy valuable space in the retractor assembly that could be used for other useful mechanisms, such as load-limiting devices.
The present invention provides a safety belt pretensioner that works independently of the safety belt retractor. Prior to function, it remains operatively independent from safety belt or retractor operations. During a collision, and when the retractor locks up the safety spool during impact, the pretensioner assembly pulls in safety belt webbing from the shoulder loop direction. After the collision, the safety belt is free to slide through the pretensioner assembly for load-limiting webbing payout, or post-impact belt take-up by the retractor.
The pretensioner assembly embodiments disclosed herein obviate damage to the retractor due to chemical abrasion and application of excessive forces. Also, as the pretensioner assembly disclosed herein is positioned separate from the retractor, it does not occupy space in the retractor assembly, thereby permitting a corresponding reduction in the size of the retractor assembly.
During safety belt use, the belt is typically anchored to the interior of a vehicle by retractor mechanism 16 at one end of the belt and by a safety belt buckle mechanism (not shown) at an opposite end of the belt. Safety belt 12 may also pass through an intermediate guiding member, such as a shoulder loop (not shown) positioned between pretensioner assembly 10 and the buckle mechanism.
Pretensioner assembly 10 may be characterized as an “in-line” assembly because it is positioned and acts along a portion of safety belt 12 extending between retractor 16 and the buckle mechanism, rather than being incorporated into the retractor mechanism as in previous designs. For example, pretensioner assembly may be located in the vehicle B pillar between the retractor and the shoulder loop.
Typical safety belt retractor mechanisms which may be used in conjunction with the pretensioner assembly of the present invention are described in U.S. Pat. Nos. 5,743,480, 5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597,546, each incorporated herein by reference.
Referring again to
Either (or both) of guide members 24, 26 may be statically mounted or rotatably mounted to respective portions of pretensioner assembly 10. In the embodiment shown in
In the embodiment shown in
A first portion 12 a of safety belt 12 is coiled about first guide member 24 and extends between a first safety belt securement (for example, a retractor mechanism in the embodiment shown) and second guide member 26. Similarly, a second portion 12 b of safety belt 12 is coiled about second guide member 26 and extends between a first guide member 24 and a second safety belt securement (for example, a safety belt buckle mechanism, not shown).
A detent mechanism, generally designated 46, is provided for releasably securing second guide member 26 in a first position with respect to first guide member 24 prior to pretensioner activation. Detent mechanism 46 may comprise, for example, a shear pin in engagement with second guide member 26 and with another member (for example, frame 22 or an interior portion of the vehicle) that is mounted in a fixed spatial relationship with first guide member 24. In another example, detent mechanism 46 comprises a deformation (for example, a crimp) in a surface of second guide member 26 in engagement with a corresponding deformation in a surface of another member mounted in a fixed spatial relationship with first guide member 24.
Referring again to
An actuator or piston 36 is movable in housing passage 30 and has a pressure surface 38 formed thereon. In the embodiment shown, actuator 36 is essentially cylindrical and is slidingly received in cylindrical passage 30 in housing 28. Actuator 36 may be die cast, molded, or otherwise formed from metal, plastics, other suitably rigid materials, and combinations thereof. Actuator 36 might be constructed as a single piece or, alternatively, as a plurality of pieces or segments.
It should be appreciated that neither actuator 36 nor housing passage 28 need be cylindrical, and various deviations from the design of the disclosed embodiments might be made without departing from the scope of the present invention. For instance, actuator 36 and passage 30 might be flat-sided, or even rectangular in cross section.
A gas generator 40 is provided in fluid communication with first end 32 of housing passage 30 and adjacent actuator pressure surface 38 for providing a gas pressure to actuator pressure surface 38. As is known in the art, gas generator 40 includes an initiator (not shown) and a quantity of a suitable gas generant composition (also not shown) in fluid communication with the initiator. Gas generator 40 may (but not necessarily) be formed as a “micro” gas generator as disclosed in U.S. Pat. No. 6,789,485, incorporated herein by reference. Gas generants useful in conjunction with the present invention are gas generants well known to those of ordinary skill in the art including cellulose-based compositions. Other examples include those described in U.S. Pat. Nos. 5,035,757, 5,460,668, 5,756,929, and 5,872,329, each herein incorporated by reference. These compositions exemplify, but do not limit, useful gas generant compositions. A gas port 42 is formed in housing 28 to enable fluid communication between housing passage 30 and gas generator 40. Gas generator 40 may be secured to housing 28, to frame 22, or to some other suitable portion of the vehicle interior.
In operation, and referring to
As actuator 36 moves toward housing passage second end 34, force is generated on detent mechanism 46 sufficient to disengage the detent mechanism, thereby releasing second guide member 26 from securement. For example, if detent mechanism 46 comprises a shear pin, sufficient force is generated by pressure of inflation gas on pressure surface 38 to cause shearing of the pin, thereby releasing second guide member 26. The shear pin may be selected to shear at a predetermined pressure in accordance with design requirements.
Thus, as actuator 36 moves toward housing passage second end 34, second guide member 26 is pulled in the direction of arrow A via attached connecting member 44. At this time, one end of belt 12 is immobilized by retractor mechanism 16. Also, an opposite end of belt 12 is immobilized by the belt buckle mechanism, and slack exists in the portion of the belt residing between the buckle mechanism and second guide portion 26. Movement of second guide member 26 with respect to first guide member 24 effectively increases a length of a portion of the safety belt extending between second guide member 26 and the buckle mechanism, thereby removing slack from the safety belt. At the end of travel of actuator 36 within housing passage 30, second guide member 26 has also reached its limit of downward travel and, having removed the slack from belt 12, becomes an additional, temporary anchor for the safety belt.
Pretensioner assembly 20 also serves a load-limiting function. As the vehicle occupant is thrown forward into safety belt 12, a tension force is exerted on the belt, causing second guide member 26 to retract, in the direction indicated by arrow B. This causes, via connecting member 44, a movement of actuator 36 and a corresponding compression of the gas contained in housing passage 30. This motion of second guide member 26 releases a slight amount of belt webbing, helping to absorb the impact force on the occupant and to aid in minimizing belt-inflicted injury.
In another embodiment, shown in
Referring again to
It should be understood that the preceding is merely a detailed description of various embodiments of this invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention.
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|U.S. Classification||242/374, 297/480, 280/806, 297/478|
|Mar 10, 2006||AS||Assignment|
Owner name: AUTOMOTIVE SYSTEMS LABORATORY, INC., MICHIGAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:STEVENS, BRUCE A.;REEL/FRAME:017331/0798
Effective date: 20051012
|Nov 14, 2011||REMI||Maintenance fee reminder mailed|
|Apr 1, 2012||LAPS||Lapse for failure to pay maintenance fees|
|May 22, 2012||FP||Expired due to failure to pay maintenance fee|
Effective date: 20120401